Heat exchanger and refrigeration cycle apparatus including the same

ABSTRACT

A flat heat transfer tube in an outdoor heat exchanger includes a main body and a connecting portion. The flat heat transfer tube has a plurality of flow paths spaced from each other. The flat heat transfer tube has a first side portion and a second side portion spaced from each other by a width. The connecting portion connected to an opening of a header has an opening end face in which each of the flow paths opens. In the connecting portion, the first side portion is tapered toward the opening end face to be reduced in width. A first opening end of a first flow path located closest to the first side portion has a second flow path cross-sectional area smaller than a first flow path cross-sectional area of an opening end of each of other flow paths.

TECHNICAL FIELD

The present disclosure relates to a heat exchanger and a refrigerationcycle apparatus including the same.

BACKGROUND ART

An exemplary embodiment of a heat exchanger used in an air conditioneris a heat exchanger applying a flat heat transfer tube having a flatshape and provided with a plurality of flow paths through whichrefrigerant flows. When this type of heat exchanger is operated tofunction as an evaporator, it requires a larger amount of refrigerant toflow through a flow path located on the windward side in order toimprove the heat transfer performance. For example, PTL 1 proposes aheat exchanger including a flat heat transfer tube in which a flow pathlocated on the windward side is broader than a flow path located on theleeward side.

CITATION LIST Patent Literature

-   PTL 1: Japanese Patent Laying-Open No. 2015-90219

SUMMARY OF INVENTION Technical Problem

The flat heat transfer tube is manufactured, for example, by extrusionmolding of a material such as aluminum. In the case of the flat heattransfer tube in which the flow path located on the windward side isbroader than the flow path located on the leeward side, for example, itscross-sectional shape becomes asymmetrical, which may make it difficultto manufacture a desired flat heat transfer tube. The heat exchangerneeds to be improved in manufacturability while ensuring heat transferperformance.

The present disclosure has been made as part of such a development. Oneobject of the present disclosure is to provide a heat exchanger improvedin manufacturability while ensuring heat transfer performance, andanother object thereof is to provide a refrigeration cycle apparatus towhich such a heat exchanger is applied.

Solution to Problem

A heat exchanger according to the present disclosure includes a flatheat transfer tube having a flat shape, a header, and a heat dissipationfin. The flat heat transfer tube having a flat shape has a first sideportion and a second side portion spaced from each other by a width in afirst direction, and extends in a second direction crossing the firstdirection. The flat heat transfer tube has a plurality of flow pathseach extending in the second direction, the flow paths being spaced fromeach other in the first direction. The header has an opening to whichthe flat heat transfer tube is connected. The flat heat transfer tubeincludes a main body and a connecting portion. The main body is attachedto the heat dissipation fin. The connecting portion has an opening endface at which each of the flow paths opens. The connecting portion isinserted into the opening of the header and connected to the header. Inthe main body, each of the flow paths has a first flow pathcross-sectional area. In the connecting portion, the first side portionis tapered toward the opening end face to be reduced in the width. Inthe opening end face, a first opening end of a first flow path locatedclosest to the tapered first side portion among the flow paths has asecond flow path cross-sectional area smaller than the first flow pathcross-sectional area.

A refrigeration cycle apparatus according to the present disclosureincludes the heat exchanger.

Advantageous Effects of Invention

According to the heat exchanger of the present disclosure, the flat heattransfer tube includes a main body and a connecting portion. The flatheat transfer tube has a plurality of flow paths spaced from each other.The flat heat transfer tube has a first side portion and a second sideportion spaced from each other by a width. The connecting portionconnected to the opening of the header has an opening end face at whicheach of the flow paths opens. In the connecting portion, the first sideportion is tapered toward the opening end face to be reduced in width.Thereby, the connecting portion can be easily inserted into the openingof the header, which makes it possible to contribute to improvement inmanufacturability. In the opening end face, the first opening end of thefirst flow path located closest to the first side portion has a secondflow path cross-sectional area smaller than the first flow pathcross-sectional area. This allows a larger amount of refrigerant to flowthrough the flow path located in the region under high thermal load,with the result that the heat transfer performance can be ensured.

According to the refrigeration cycle apparatus of the presentdisclosure, the heat exchanger is provided, so that themanufacturability can be improved while ensuring the heat transferperformance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing a refrigerant circuit of a refrigerationcycle apparatus including an outdoor heat exchanger according to eachembodiment.

FIG. 2 is a perspective view showing an example of the outdoor heatexchanger according to each embodiment.

FIG. 3 is a partially cross-sectional top view showing a structure of aportion where a flat heat transfer tube is connected to a header in anoutdoor heat exchanger according to a first embodiment.

FIG. 4 is a cross-sectional view taken along a cross-sectional lineIV-IV shown in FIG. 3 in the first embodiment.

FIG. 5 is a front view showing an opening end face in a connectingportion of the flat heat transfer tube in the first embodiment.

FIG. 6 shows an example of a flowchart illustrating a method ofmanufacturing an outdoor heat exchanger in the first embodiment.

FIG. 7 is a partial top view showing one step of the method ofmanufacturing the outdoor heat exchanger in the first embodiment.

FIG. 8 is a partially cross-sectional top view showing a step performedafter the step shown in FIG. 7 in the first embodiment.

FIG. 9 is a diagram for illustrating functions and effects of theoutdoor heat exchanger in the first embodiment.

FIG. 10 is a partially cross-sectional top view showing a structure of aportion where a flat heat transfer tube is connected to a header in anoutdoor heat exchanger according to a second embodiment.

FIG. 11 is a front view showing an opening end face in a connectingportion of the flat heat transfer tube in the second embodiment.

FIG. 12 is a partial top view showing one step of a method ofmanufacturing an outdoor heat exchanger in the second embodiment.

FIG. 13 is a partially cross-sectional top view showing a structure of aportion where a flat heat transfer tube is connected to a header in anoutdoor heat exchanger according to a third embodiment.

FIG. 14 is a front view showing an opening end face in a connectingportion of the flat heat transfer tube in the third embodiment.

FIG. 15 is a partial top view showing one step of a method ofmanufacturing an outdoor heat exchanger in the third embodiment.

FIG. 16 is a partially cross-sectional partial top view showing a stepperformed after the step shown in FIG. 15 in the third embodiment.

FIG. 17 is a partially cross-sectional top view showing a structure of aportion where a flat heat transfer tube is connected to a header in anoutdoor heat exchanger according to a fourth embodiment.

FIG. 18 is a front view showing an opening end face in a connectingportion of the flat heat transfer tube in the fourth embodiment.

FIG. 19 is a partial top view showing one step of a method ofmanufacturing an outdoor heat exchanger in the fourth embodiment.

FIG. 20 is a perspective view showing another example of the outdoorheat exchanger according to each embodiment.

DESCRIPTION OF EMBODIMENTS

The following first describes an example of a refrigerant circuit of arefrigeration cycle apparatus including a heat exchanger (an outdoorheat exchanger) according to each embodiment. As shown in FIG. 1 , arefrigeration cycle apparatus 1 includes a compressor 3, an indoor heatexchanger 5, a fan 7, an expansion valve 9, an outdoor heat exchanger11, a propeller fan 13, a four-way valve 15, and a refrigerant pipe 17that connects these components. The structure of outdoor heat exchanger11 will be described in detail in each embodiment.

The following describes the operation of the above-mentionedrefrigeration cycle apparatus 1 in the case of a heating operation. Theflow of refrigerant during a heating operation is indicated by a solidline. By driving compressor 3, high-temperature and high-pressure gasrefrigerant is discharged from compressor 3. The dischargedhigh-temperature and high-pressure gas refrigerant (a single phase)flows through four-way valve 15 into indoor heat exchanger 5.

Indoor heat exchanger 5 exchanges heat between the gas refrigerantflowing thereinto and the air fed thereinto by fan 7. Thehigh-temperature and high-pressure gas refrigerant is condensed intohigh-pressure liquid refrigerant (a single phase). The heat-exchangedair is fed out from indoor heat exchanger 5 into an indoor side to heatthe indoor side. The high-pressure liquid refrigerant fed out fromindoor heat exchanger 5 is converted by expansion valve 9 intorefrigerant in a two-phase state including low-pressure gas refrigerantand liquid refrigerant.

The refrigerant in the two-phase state flows into outdoor heat exchanger11. Outdoor heat exchanger 11 functions as an evaporator. Outdoor heatexchanger 11 exchanges heat between the refrigerant in the two-phasestate flowing thereinto and the air fed thereinto by propeller fan 13.From the refrigerant in the two-phase state, liquid refrigerantevaporates to become low-pressure gas refrigerant (a single phase). Atthis time, a larger amount of refrigerant flows through the refrigerantflow path located on the windward side than through the refrigerant flowpath located on the leeward side. The low-pressure gas refrigerant isfed out from outdoor heat exchanger 11.

The low-pressure gas refrigerant fed out from outdoor heat exchanger 11flows into compressor 3 through four-way valve 15. The low-pressure gasrefrigerant having flowed into compressor 3 is compressed intohigh-temperature and high-pressure gas refrigerant, which is thendischarged from compressor 3 again. This cycle is subsequently repeated.

The following describes the case of a cooling operation. By drivingcompressor 3, high-temperature and high-pressure gas refrigerant isdischarged from compressor 3. The discharged high-temperature andhigh-pressure gas refrigerant (a single phase) flows into outdoor heatexchanger 11 through four-way valve 15. Outdoor heat exchanger 11functions as a condenser. Outdoor heat exchanger 11 exchanges heatbetween the refrigerant flowing thereinto and the air fed thereinto bypropeller fan 13. The high-temperature and high-pressure gas refrigerantis condensed into high-pressure liquid refrigerant (a single phase).

The high-pressure liquid refrigerant fed out from outdoor heat exchanger11 is converted by expansion valve 9 into refrigerant in a two-phasestate including low-pressure gas refrigerant and liquid refrigerant. Therefrigerant in the two-phase state flows into indoor heat exchanger 5.Indoor heat exchanger 5 exchanges heat between the refrigerant in thetwo-phase state flowing thereinto and the air fed thereinto by fan 7.From the refrigerant in the two-phase state, liquid refrigerantevaporates to become low-pressure gas refrigerant (a single phase). Theheat-exchanged air is fed out from indoor heat exchanger 5 into anindoor side to cool the indoor side.

The low-pressure gas refrigerant fed out from indoor heat exchanger 5flows into compressor 3 through four-way valve 15. The low-pressure gasrefrigerant having flowed into compressor 3 is compressed intohigh-temperature and high-pressure gas refrigerant, which is thendischarged from compressor 3 again. This cycle is subsequently repeated.Then, the structure of outdoor heat exchanger 11 according to eachembodiment will be described below. Each embodiment will be describedwith reference to an X-axis and a Y-axis for convenience of explanation.

First Embodiment

The following describes an example of an outdoor heat exchanger as aheat exchanger according to the first embodiment. As shown in FIG. 2 , ahousing 10 of an outdoor unit accommodates: outdoor heat exchanger 11including a flat heat transfer tube 21 and a heat dissipation fin 41;and a header 31. In this case, a single row-type outdoor heat exchanger11 is disposed. Further, housing 10 also accommodates propeller fan 13,compressor 3 (not shown), and the like. By driving propeller fan 13 (notshown), air flows inside housing 10 in the direction indicated by anarrow Y1.

As shown in FIG. 3 , flat heat transfer tube 21 in outdoor heatexchanger 11 includes a main body 23 and a connecting portion 25. Flatheat transfer tube 21 has a width in a Y-axis direction as the firstdirection and extends in an X-axis direction as the second direction. Inflat heat transfer tube 21, a plurality of flow paths 27 each extendingin the X-axis direction are spaced from each other in the Y-axisdirection (see FIG. 4 ).

Flat heat transfer tube 21 has a first side portion 29 a and a secondside portion 29 b that are spaced from each other by a width. In thiscase, first side portion 29 a is located on the leeward side whilesecond side portion 29 b is located on the windward side. Heatdissipation fin 41 is attached to main body 23.

Connecting portion 25 has an opening end face 26 at which an opening end28 (see FIG. 5 ) of each of the plurality of flow paths 27 is located.In this case, opening end face 26 is located to extend in the Y-axisdirection. Connecting portion 25 is connected to header 31 while beinginserted into an opening 33 provided in header 31. First side portion 29a and second side portion 29 b in connecting portion 25 are in contactwith an opening inner wall surface 34 of opening 33. As shown in FIG. 4, in main body 23, each of the plurality of flow paths 27 has a firstflow path cross-sectional area Si. As will be described later, when flatheat transfer tube 21 is manufactured, a molded body to be formed asmain body 23 is first manufactured.

As shown in FIGS. 3 and 5 , connecting portion 25 is processed (shrunk)so as to shrink flat heat transfer tube 21 in a width direction (theY-axis direction). In connecting portion 25, first side portion 29 a istapered toward opening end face 26 to be reduced in width. At openingend face 26, a first opening end 28 a of a first flow path 27 a locatedclosest to first side portion 29 a among flow paths 27 arranged in theY-axis direction is narrowed in the Y-axis direction so as to conform tothe tapered first side portion 29 a.

Thus, first opening end 28 a of first flow path 27 a has a second flowpath cross-sectional area S2 smaller than first flow pathcross-sectional area S1 of opening end 28 of each of other flow paths27. In other words, first opening end 28 a of first flow path 27 alocated closest to first side portion 29 a has second flow pathcross-sectional area S2 smaller than first flow path cross-sectionalarea S1 of opening end 28 of each of other flow paths 27. Outdoor heatexchanger 11 according to the first embodiment is configured asdescribed above.

The following describes an example of a method of manufacturing outdoorheat exchanger 11 described above based on a flowchart. As shown in FIG.6 , in step Ti, a material to be formed as a flat heat transfer tube isfirst prepared. Then, in step T2, the material is introduced into anextruder. Then, in step T3, the material introduced into the extruder isextruded to thereby produce molded body 20 (see FIG. 7 ) to be formed asa flat heat transfer tube.

At this time, by performing extrusion molding such that each of flowpaths 27 (see FIG. 4 ) has first flow path cross-sectional area Si,molded body 20 (see FIG. 7 ) is formed to have a cross-sectional shapethat is line-symmetric with respect to the center line in the widthdirection as shown by the cross-sectional shape of main body 23 (seeFIG. 4 ). This allows uniform extrusion of the material, for example, tomake it possible to produce a molded body with no void.

Then, in step T4, molded body 20 is cut and shrunk (see FIG. 7 ). Asshown in FIG. 7 , in this case, molded body 20 is cut in the Y-axisdirection. At the cut surface of this cut molded body 20, each of flowpaths 27 (see FIG. 4 and the like) opens as opening end face 26.

At this time, molded body 20 is cut as well as shrunk. Specifically,pressure is applied (see an arrow P1), for example, with a plate member(not shown) or the like to first side portion 29 a of molded body 20 soas to taper this first side portion 29 a such that molded body 20 isreduced in width toward opening end face 26.

Since first side portion 29 a is tapered, at opening end face 26, firstopening end 28 a of first flow path 27 a located closest to first sideportion 29 a among the plurality of flow paths 27 is narrowed in theY-axis direction (see FIG. 5 ). Thus, first opening end 28 a of firstflow path 27 a located closest to first side portion 29 a is to havesecond flow path cross-sectional area S2 smaller than first flow pathcross-sectional area S1 of opening end 28 of each of other flow paths27. In this way, flat heat transfer tube 21 including main body 23 andconnecting portion 25 is completed (step T5).

Then, in step T6, flat heat transfer tube 21 is connected to header 31(see FIG. 8 ). As shown in FIG. 8 , connecting portion 25 of flat heattransfer tube 21 is inserted into opening 33 provided in header 31 asshown by an arrow P3, and first side portion 29 a and second sideportion 29 b are brought into contact with opening inner wall surface 34of opening 33.

At this time, since first side portion 29 a is tapered, connectingportion 25 is easily inserted into opening 33 of header 31. Further, thelength of the portion of connecting portion 25 that is inserted intoheader 31 is uniquely defined, so that connecting portion 25 can beprevented, for example, from being inserted more than necessary intoopening 33 of header 31. Thus, attachment of flat heat transfer tube 21onto header 31 ends, and the main part of outdoor heat exchanger 11 iscompleted.

According to the above-described outdoor heat exchanger 11, whenmanufacturing a molded body to be formed as flat heat transfer tube 21,a molded body having a cross-sectional shape that is line-symmetric withrespect to the center line in the width direction is first molded asshown by the cross-sectional shape of main body 23 (see FIG. 4 ). Thisallows uniform extrusion of the material, for example, to make itpossible to produce a molded body with no void, and also possible tocontribute to improvement in manufacturability of outdoor heat exchanger11.

Then, flat heat transfer tube 21 manufactured from the molded body isprovided with tapered first side portion 29 a, so that themanufacturability can be improved while ensuring the heat transferperformance, which will be described below.

As shown in FIG. 2 , in outdoor heat exchanger 11 in refrigeration cycleapparatus 1, heat is exchanged between the air fed into outdoor heatexchanger 11 (see arrow Y1) and the refrigerant flowing through flatheat transfer tube 21. When outdoor heat exchanger 11 functions as anevaporator, the air fed into outdoor heat exchanger 11 exchanges heatwith the refrigerant flowing through flat heat transfer tube 21, andthus, the temperature of the air lowers from the windward side to theleeward side.

In other words, as shown in FIG. 9 (in the middle stage), the thermalload decreases with increasing ventilation distance in which air flowsfrom the windward side to the leeward side. In the region (range) underhigh thermal load, heat exchange between air and refrigerant is activelyperformed. Thus, in the case where a heat exchanger functions as anevaporator, if the refrigerant is completely gasified by heat exchangewith air, the heat transfer performance cannot be improved.

Thus, as shown in FIG. 9 (in the upper stage), processing (shrinking) isperformed onto the cut portion of molded body 20 to be formed asconnecting portion 25 of flat heat transfer tube 21 with respect to theportion to be formed as a main body of flat heat transfer tube 21 suchthat the flow rate of the refrigerant flowing on the windward side ishigher than the flow rate of the refrigerant flowing on the leewardside. In other words, first side portion 29 a is processed (shrunk) tobe tapered toward opening end face 26 to be reduced in width (from awidth W1 to a width W2).

Therefore, in connecting portion 25 of flat heat transfer tube 21, firstopening end 28 a of first flow path 27 a located closest to first sideportion 29 a located on the leeward side is to be narrowed in the Y-axisdirection so as to conform to the tapered first side portion 29 a.Thereby, first opening end 28 a is to have second flow pathcross-sectional area S2 smaller than first flow path cross-sectionalarea S1 of opening end 28 of each of other flow paths 27.

By the structure in which second flow path cross-sectional area S2 offirst opening end 28 a of first flow path 27 a located on the leewardside is smaller than first flow path cross-sectional area S1 of openingend 28 of each of other flow paths 27, as shown in FIG. 9 (in the lowerstage), the refrigerant less easily flows through first flow path 27 a,and accordingly, more refrigerant flows through flow path 27 located onthe windward side or the like under high thermal load, so that completegasification of the refrigerant can be suppressed. As a result, the heattransfer performance as outdoor heat exchanger 11 can be ensured.

Further, in outdoor heat exchanger 11 as described above, first sideportion 29 a of connecting portion 25 of flat heat transfer tube 21connected to header 31 is tapered, which makes it easy to insert it intoopening 33 formed in header 31. This makes it possible to contribute toimprovement in manufacturability of outdoor heat exchanger 11.

Further, since the tapered first side portion 29 a of connecting portion25 comes into contact with opening inner wall surface 34 of opening 33,the length of the portion of connecting portion 25 (flat heat transfertube 21) that is inserted into header 31 is uniquely defined. Thereby,connecting portion 25 can be prevented, for example, from being insertedmore than necessary into opening 33 of header 31. This can consequentlycontribute to stabilization of the flow of the refrigerant inside header31.

Second Embodiment

The following describes an example of an outdoor heat exchanger as aheat exchanger according to the second embodiment. As shown in FIGS. 10and 11 , opening end face 26 of flat heat transfer tube 21 is located toextend from first side portion 29 a to second side portion 29 b in athird direction inclined toward main body 23 with respect to the Y-axisdirection.

In connecting portion 25 of flat heat transfer tube 21, first sideportion 29 a is tapered toward opening end face 26 to be reduced inwidth. First opening end 28 a of first flow path 27 a located closest tofirst side portion 29 a has second flow path cross-sectional area S2smaller than first flow path cross-sectional area S1 of opening end 28of each of other flow paths 27.

Since the configurations other than the above are the same as those ofoutdoor heat exchanger 11 shown in FIGS. 3 to 5 , the same members aredenoted by the same reference characters, and the description thereofwill not be repeated unless necessary.

The following describes an example of a method of manufacturing outdoorheat exchanger 11 described above. After the processes similar to thosein steps T1, T2, and T3 shown in FIG. 6 are performed, the molded bodyis cut and shrunk (step T4).

As shown in FIG. 12 , in this case, molded body 20 is cut in a directioninclined with respect to the Y-axis direction. At the cut surface of thecut molded body 20, each of the plurality of flow paths 27 (see FIG. 11) opens as opening end face 26. At this time, molded body 20 is cut aswell as shrunk. Specifically, pressure is applied (see arrow P1), forexample, with a plate member (not shown) or the like to first sideportion 29 a of molded body 20 so as to taper this first side portion 29a such that molded body 20 is reduced in width toward opening end face26.

By the tapered first side portion 29 a, at opening end face 26, firstopening end 28 a of first flow path 27 a located closest to first sideportion 29 a among the plurality of flow paths 27 is to have second flowpath cross-sectional area S2 smaller than first flow pathcross-sectional area S1 of opening end 28 of each of other flow paths27. In this way, flat heat transfer tube 21 including main body 23 andconnecting portion 25 is completed (step T5). Then, through the similarprocess in step T6, attachment of flat heat transfer tube 21 onto header31 ends, and the main part of outdoor heat exchanger 11 is completed.

According to outdoor heat exchanger 11 described above, the followingeffects are achieved in addition to the effects achieved by outdoor heatexchanger 11 described in the first embodiment.

In connecting portion 25 of flat heat transfer tube 21 of outdoor heatexchanger 11 described above, opening end face 26 is located to extendfrom first side portion 29 a located on the leeward side to second sideportion 29 b located on the windward side in the direction inclinedtoward main body 23 with respect to the Y-axis direction.

Thus, second flow path 27 b located on the leeward side is longer thanfirst flow path 27 a located on the windward side. Thereby, the flowpath resistance (friction resistance) of second flow path 27 b locatedon the leeward side becomes higher than the flow path resistance(friction resistance) of first flow path 27 a located on the windwardside, so that the refrigerant easily flows through second flow path 27 blocated on the windward side.

Thus, by the tapered first side portion 29 a, a still larger amount ofrefrigerant flows through flow path 27 located on the windward sideunder high thermal load in combination with the effect of making therefrigerant less easily flow through first flow path 27 a located on theleeward side. As a result, the heat transfer performance as outdoor heatexchanger 11 can be improved.

Third Embodiment

The following describes an example of an outdoor heat exchanger as aheat exchanger according to the third embodiment. As shown in FIGS. 13and 14 , opening end face 26 of flat heat transfer tube 21 is located toextend in the Y-axis direction.

In connecting portion 25 of flat heat transfer tube 21, first sideportion 29 a is tapered toward opening end face 26 to be reduced inwidth. First opening end 28 a of first flow path 27 a located closest tofirst side portion 29 a has second flow path cross-sectional area S2smaller than first flow path cross-sectional area S1 of opening end 28of each of other flow paths 27.

Further, in connecting portion 25, second side portion 29 b is taperedtoward opening end face 26 to be reduced in width. Second opening end 28b of second flow path 27 b located closest to second side portion 29 bhas a third flow path cross-sectional area S3 smaller than first flowpath cross-sectional area S1 of opening end 28 of each of other flowpaths 27 and larger than second flow path cross-sectional area S2.

Since the configurations other than the above are the same as those ofoutdoor heat exchanger 11 shown in FIGS. 3 to 5 , the same members aredenoted by the same reference characters, and the description thereofwill not be repeated unless necessary.

The following describes an example of a method of manufacturing outdoorheat exchanger 11 described above. After the processes similar to thosein steps T1, T2, and T3 shown in FIG. 6 are performed, the molded bodyis cut and shrunk (step T4).

As shown in FIG. 15 , molded body 20 is cut in the Y-axis direction. Atthe cut surface of the cut molded body 20, each of the plurality of flowpaths 27 (see FIG. 14 ) opens as opening end face 26. At this time,along with cutting of molded body 20, first side portion 29 a and secondside portion 29 b in molded body 20 are tapered toward opening end face26 such that molded body 20 is reduced in width.

First side portion 29 a is tapered by applying pressure (pressure A: seean arrow P1). Also, second side portion 29 b is tapered by applyingpressure lower than pressure A (pressure B: see an arrow P2).

Under the condition that the magnitude relation of the pressure appliedfor tapering is pressure A>pressure B, at opening end face 26, secondopening end 28 b of second flow path 27 b located closest to second sideportion 29 b is shorter in length narrowed in the Y-axis direction thanfirst opening end 28 a of first flow path 27 a located closest to firstside portion 29 a.

Thereby, as shown in FIG. 14 , second opening end 28 b of second flowpath 27 b is formed to have third flow path cross-sectional area S3larger than second flow path cross-sectional area S2 of first openingend 28 a of first flow path 27 a. Thus, flat heat transfer tube 21including main body 23 and connecting portion 25 is completed (step T5).

Then, in step T6, flat heat transfer tube 21 is connected to header 31(see FIG. 16 ). As shown in FIG. 16 , connecting portion 25 of flat heattransfer tube 21 is inserted into opening 33 provided in header 31 asshown by an arrow P3, and first side portion 29 a and second sideportion 29 b are brought into contact with opening inner wall surface 34of opening 33.

At this time, since both first side portion 29 a and second side portion29 b are tapered, connecting portion 25 is easily inserted into opening33 of header 31. Further, the length of the portion of connectingportion 25 that is inserted into header 31 is uniquely defined, so thatconnecting portion 25 can be prevented, for example, from being insertedmore than necessary into opening 33 of header 31. Thus, attachment offlat heat transfer tube 21 onto header 31 ends, and the main part ofoutdoor heat exchanger 11 is completed.

According to outdoor heat exchanger 11 described above, the followingeffects are achieved in addition to the effects achieved by outdoor heatexchanger 11 described in the first embodiment.

In connecting portion 25 in flat heat transfer tube 21 of outdoor heatexchanger 11 as described above, first side portion 29 a and second sideportion 29 b each are tapered. Thereby, when connecting portion 25 offlat heat transfer tube 21 is connected to header 31, this connectingportion 25 is more easily inserted into opening 33 provided in header 31as compared with the case where only first side portion 29 a is tapered.This can consequently contribute to improvement in manufacturability ofoutdoor heat exchanger 11.

Further, when the tapered first side portion 29 a and the tapered secondside portion 29 b in connecting portion 25 come into contact withopening inner wall surface 34 of opening 33, the length of the portionof connecting portion 25 (flat heat transfer tube 21) that is insertedinto header 31 is more reliably defined. Thereby, connecting portion 25can be prevented from being inserted more than necessary into opening 33of header 31. This can consequently contribute to stabilization of theflow of the refrigerant inside header 31.

Further, at opening end face 26 in connecting portion 25, second openingend 28 b of second flow path 27 b located closest to second side portion29 b has third flow path cross-sectional area S3 smaller than first flowpath cross-sectional area S1 of opening end 28 of each of other flowpaths 27 and larger than second flow path cross-sectional area S2.

Thereby, for second flow path 27 b located on the windward side throughwhich a larger amount of refrigerant is required to flow, second sideportion 29 b on the windward side is tapered to thereby make it possibleto minimize that the refrigerant less easily flows through second flowpath 27 b. As a result, the heat transfer performance as outdoor heatexchanger 11 can be maintained.

Fourth Embodiment

The following describes an example of an outdoor heat exchanger as aheat exchanger according to the fourth embodiment. As shown in FIGS. 17and 18 , opening end face 26 of flat heat transfer tube 21 is located toextend from first side portion 29 a to second side portion 29 b in thethird direction inclined toward main body 23 with respect to the Y-axisdirection.

In connecting portion 25 of flat heat transfer tube 21, first sideportion 29 a is tapered toward opening end face 26 to be reduced inwidth. First opening end 28 a of first flow path 27 a located closest tofirst side portion 29 a has second flow path cross-sectional area S2smaller than first flow path cross-sectional area S1 of opening end 28of each of other flow paths 27.

Second side portion 29 b is tapered toward opening end face 26 to bereduced in width. Second opening end 28 b of second flow path 27 blocated closest to second side portion 29 b has third flow pathcross-sectional area S3 smaller than first flow path cross-sectionalarea S1 of opening end 28 of each of other flow paths 27 and larger thansecond flow path cross-sectional area S2.

Since the configurations other than the above are the same as those ofoutdoor heat exchanger 11 shown in FIGS. 3 to 5 , the same members aredenoted by the same reference characters, and the description thereofwill not be repeated unless necessary.

The following describes an example of a method of manufacturing outdoorheat exchanger 11 described above. After the processes similar to thosein steps T1, T2, and T3 shown in FIG. 6 are performed, the molded bodyis cut and shrunk (step T4).

As shown in FIG. 19 , in this case, molded body 20 is cut in a directioninclined with respect to the Y-axis direction. At the cut surface of thecut molded body 20, each of the plurality of flow paths 27 (see FIG. 18) opens as opening end face 26. At this time, along with cutting ofmolded body 20, first side portion 29 a and second side portion 29 b inmolded body 20 are tapered toward opening end face 26 such that moldedbody 20 is reduced in width.

First side portion 29 a is tapered by applying pressure (pressure A: seean arrow P1). Also, second side portion 29 b is tapered by applyingpressure lower than pressure A (pressure B: see an arrow P2).

Under the condition that the magnitude relation of the pressure appliedfor tapering is pressure A>pressure B, at opening end face 26, secondopening end 28 b of second flow path 27 b located closest to second sideportion 29 b is shorter in length narrowed in the Y-axis direction thanfirst opening end 28 a of first flow path 27 a located closest to firstside portion 29 a.

Thereby, as shown in FIG. 18 , second opening end 28 b of second flowpath 27 b is formed to have third flow path cross-sectional area S3larger than second flow path cross-sectional area S2 of first openingend 28 a of first flow path 27 a. Thus, flat heat transfer tube 21including main body 23 and connecting portion 25 is completed (step T5).

Then, in step T6, flat heat transfer tube 21 is connected to header 31.At this time, since both first side portion 29 a and second side portion29 b are tapered, connecting portion 25 is easily inserted into opening33 of header 31. Further, the length of the portion of connectingportion 25 that is inserted into header 31 is uniquely defined, so thatconnecting portion 25 can be prevented, for example, from being insertedmore than necessary into opening 33 of header 31. Thus, attachment offlat heat transfer tube 21 onto header 31 ends, and the main part ofoutdoor heat exchanger 11 is completed.

Outdoor heat exchanger 11 described above can achieve both the effectachieved by outdoor heat exchanger 11 described in the second embodimentand the effect achieved by outdoor heat exchanger 11 described in thethird embodiment.

In connecting portion 25 in flat heat transfer tube 21 of outdoor heatexchanger 11 described above, opening end face 26 is located to extendfrom first side portion 29 a to second side portion 29 b in thedirection inclined toward main body 23 with respect to the Y-axisdirection.

Thereby, first flow path 27 a becomes longer than second flow path 27 b,and the flow path resistance (friction resistance) of first flow path 27a becomes higher than the flow path resistance (friction resistance) ofsecond flow path 27 b, so that the refrigerant easily flows throughsecond flow path 27 b located on the windward side.

Further, in connecting portion 25, both first side portion 29 a andsecond side portion 29 b are tapered. At opening end face 26 inconnecting portion 25, second opening end 28 b of second flow path 27 blocated closest to second side portion 29 b has third flow pathcross-sectional area S3 smaller than first flow path cross-sectionalarea S1 of opening end 28 of each of other flow paths 27 and larger thansecond flow path cross-sectional area S2.

Thereby, for second flow path 27 b located on the windward side throughwhich a larger amount of refrigerant is required to flow, second sideportion 29 b on the windward side is tapered to thereby make it possibleto minimize that the refrigerant less easily flows through second flowpath 27 b. As a result, the heat transfer performance as outdoor heatexchanger 11 can be maintained.

Further, in connecting portion 25, first side portion 29 a and secondside portion 29 b each are tapered, so that this connecting portion 25is more easily inserted into opening 33 provided in header 31. This canconsequently contribute to improvement in manufacturability of outdoorheat exchanger 11.

Further, the tapered first side portion 29 a and the tapered second sideportion 29 b in connecting portion 25 come into contact with openinginner wall surface 34 of opening 33, so that connecting portion 25 canbe prevented, for example, from being inserted more than necessary intoopening 33 of header 31. This can consequently contribute tostabilization of the flow of the refrigerant inside header 31.

In each of the above-described embodiments, a single-row type outdoorheat exchanger 11 has been explained by way of example (see FIG. 2 ).Outdoor heat exchanger 11 may however be of a multi-row type and may bea two-row type outdoor heat exchanger 11 in which an outdoor heatexchanger 11 a and an outdoor heat exchanger 11 b are arranged in thedirection in which air flows, as shown in FIG. 20 .

Also in such outdoor heat exchanger 11, each of outdoor heat exchangers11 according to the first to fourth embodiments is applicable to: aportion of outdoor heat exchanger 11 a where a flat heat transfer tubeis connected to a header 31 a; and a portion of outdoor heat exchanger11 b where a flat heat transfer tube is connected to a header 31 b, eachof these portions being shown inside a dotted-line frame DL.

Further, an outdoor heat exchanger in which three or more rows ofoutdoor heat exchangers are arranged may be applicable. Further, thepresent invention is applicable not only to outdoor heat exchanger 11but also to indoor heat exchanger 5 as required.

The outdoor heat exchangers described in the respective embodiments canbe variously combined with one another as required.

The embodiments disclosed herein are by way of example and not limitedas described. The present disclosure is defined by the terms of theclaims, rather than the description above, and is intended to includeany modifications within the meaning and scope equivalent to the termsof the claims.

INDUSTRIAL APPLICABILITY

The present disclosure is effectively applicable to a heat exchangerincluding a flat heat transfer tube.

REFERENCE SIGNS LIST

1 refrigeration cycle apparatus, 3 compressor, 5 indoor heat exchanger,7 fan, 9 expansion valve, 10 housing, 11 outdoor heat exchanger, 13propeller fan, 15 four-way valve, 17 refrigerant pipe, 20 molded body,21 flat heat transfer tube, 23 main body, 25 connecting portion, 26opening end face, 27 flow path, 27 a first flow path, 27 b second flowpath, 28 opening end, 28 a first opening end, 28 b second opening end,29 a first side portion, 29 b second side portion, 31 header, 33opening, 34 opening inner wall surface, 41 heat dissipation fin, S1first flow path cross-sectional area, S2 second flow pathcross-sectional area, S3 third flow path cross-sectional area, Y1, P1,P2, P3 arrow (insertion), DL frame.

1. A heat exchanger comprising: a flat heat transfer tube having a flatshape, having a first side portion and a second side portion spaced fromeach other by a width in a first direction, extending in a seconddirection crossing the first direction, and having a plurality of flowpaths each extending in the second direction, the flow paths beingspaced from each other in the first direction; a header having anopening to which the flat heat transfer tube is connected; and a heatdissipation fin, wherein the flat heat transfer tube comprises a mainbody attached to the heat dissipation fin, and a connecting portionhaving an opening end face at which each of the flow paths opens, theconnecting portion being inserted into the opening of the header andconnected to the header, in the main body, each of the flow paths has afirst flow path cross-sectional area, in the connecting portion, onlythe first side portion is tapered toward the opening end face to bereduced in the width, and in the opening end face, a first opening endof a first flow path located closest to the tapered first side portionamong the flow paths has a second flow path cross-sectional area smallerthan the first flow path cross-sectional area.
 2. (canceled)
 3. The heatexchanger according to claim 1, wherein the tapered first side portionis in contact with an opening inner wall surface in the opening of theheader.
 4. (canceled)
 5. The heat exchanger according to claim 1,wherein the opening end face is located to extend in the firstdirection.
 6. The heat exchanger according to claim 1, wherein theopening end face is located to extend from the first side portion to thesecond side portion to extend toward the main body in a third directioncrossing the first direction.
 7. The heat exchanger according to claim1, wherein the flat heat transfer tube is disposed such that the firstside portion is located on a leeward side and the second side portion islocated on a windward side.
 8. A refrigeration cycle apparatuscomprising the heat exchanger according to claim
 1. 9. A heat exchangercomprising: a flat heat transfer tube having a flat shape, having afirst side portion and a second side portion spaced from each other by awidth in a first direction, extending in a second direction crossing thefirst direction, and having a plurality of flow paths each extending inthe second direction, the flow paths being spaced from each other in thefirst direction; a header having an opening to which the flat heattransfer tube is connected; and a heat dissipation fin, wherein the flatheat transfer tube comprises a main body attached to the heatdissipation fin, and a connecting portion having an opening end face atwhich each of the flow paths opens, the connecting portion beinginserted into the opening of the header and connected to the header, inthe main body, each of the flow paths has a first flow pathcross-sectional area, in the connecting portion, the first side portionis tapered toward the opening end face to be reduced in the width, inthe opening end face, a first opening end of a first flow path locatedclosest to the tapered first side portion among the flow paths has asecond flow path cross-sectional area smaller than the first flow pathcross-sectional area, in the connecting portion, the second side portionis tapered toward the opening end face to be reduced in the width, inthe opening end face, a second opening end of a second flow path locatedclosest to the tapered second side portion among the flow paths arrangedin the first direction has a third flow path cross-sectional areasmaller than the first flow path cross-sectional area and larger thanthe second flow path cross-sectional area, and in the connectingportion, the first side portion is tapered more inward in the widthdirection of the flat heat transfer tube than the second side portion.10. The heat exchanger according to claim 9, wherein the tapered firstside portion is in contact with an opening inner wall surface in theopening of the header, and the tapered second side portion is in contactwith the opening inner wall surface in the opening of the header. 11.The heat exchanger according to claim 9, wherein the opening end face islocated to extend in the first direction.
 12. The heat exchangeraccording to claim 9, wherein the opening end face is located to extendfrom the first side portion to the second side portion to extend towardthe main body in a third direction crossing the first direction.
 13. Theheat exchanger according to claim 9, wherein the flat heat transfer tubeis disposed such that the first side portion is located on a leewardside and the second side portion is located on a windward side.
 14. Arefrigeration cycle apparatus comprising the heat exchanger according toclaim 9.